Thispapergivesashortintroductiontoandsurveyofsubspaceidentificationalgorithms.Deterministic,stochasticandcombineddeterministic-stochasticsubspaceidentificationalgorithmsaretreated.Thesemethodsestimatestatesequencesdirectlyfromthegivendata,eitherexplicitlyorimplicitly,throughanorthogonalorobli